This section describes the NDMP features supported by OneFS.

NDMP backup has two types of backup. OneFS NDMP supports tar and dump backup formats for backup. An NDMP backup session can either be a full backup or an incremental backup. OneFS NDMP supports tar and dump backup formats for backup.

• Full backup: A full backup backs up all files and directories under a path.
• Incremental backup: An incremental backup backs up changed files under the same path of a full backup.

OneFS provides the following NDMP features to back up files. The features give users more flexibility for NDMP backups.

• Level-based backup: OneFS NDMP supports full backups (level 0) and incremental (levels 1 to 9) backups. The first backup of a path must be a full backup. Thereafter, incremental backup backs up the changed files since the last full or lower-level backup. OneFS detects the changed files or directories by ctime (change time) or mtime (modification time) of objects. All subsequent level 9 incremental backups will become cumulative incremental backups after performing a level 9 incremental backup. You can run a full backup before resuming the differential incremental backups. OneFS NDMP also supports incremental forever (level 10) backup. This backup level only backs up the changed files since the most recent incremental (levels 1 to 9) backup or the last incremental forever (level 10) backup. A DMA can pass the LEVEL environment variable to specify a file path.
• Token-based backup: Token-based backups use a timestamp to extend the level-based backups. With a token-based backup, the backup backs up the changed files after the timestamp. OneFS detects the changed files or directories by ctime (change time) or mtime (modification time) of objects. A timestamp 0 forces a full backup. A DMA can pass a timestamp value for a file path in the BASE_DATE environment variable.
• Snapshot-based incremental backup: A snapshot-based incremental backup (referred to as faster-incremental backup) leverages snapshots to identify files to be backed up. For each snapshot-based incremental backup, OneFS identifies the changed files between two snapshots. One snapshot is from the prior level backup, the other snapshot is from the current backup. OneFS retains the snapshot for backup that is used to identify the changed files when the next level backup is performed. During a snapshot-based incremental backup, OneFS does not walk through all whole dataset and check timestamp of each file to identify files to be backed up. OneFS can perform a snapshot-based incremental backup significantly faster if the change rate is low. You can set the BACKUP_MODE environment variable to SNAPSHOT to enable snapshot-based incremental backups. This feature is integrated with Avamar without setting the BACKUP_MODE environment variable. The following table shows DMA support for snapshot-based incremental backups.

Table 2.      DMA support for snapshot-based incremental backups

• Multi-stream backup: A multi-stream backup runs multiple backup sessions on the same dataset. OneFS supports the NDMP multi-stream backup in OneFS 8.0.0.0 and later releases. With multi-stream backup, you can use your DMA to specify multiple streams of data to back up concurrently.
• File list backup: File list backup allows users to back up files in the file list based on the BACKUP_FILE_LIST environment variable setting. Only Networker and Symantec NetBackup can pass the BACKUP_FILE_LIST environment variable to specify a file path. During a file list backup, OneFS does not walk through the entire backup directory for backing up files.
• Backup Restartable Extension (BRE): Starting from OneFS 7.1.0, OneFS supports the NDMP BRE feature that allows to resumption of a failed backup job from the last checkpoint taken before the failure. Restartable backups are supported for NetWorker 8.1 and later versions and Commvault DMAs. You can enable restartable backups in your DMA.
• Multi-stream Backup Restartable Extension (MSBRE): Starting from OneFS 9.1.0.0, OneFS supports the NDMP MSBRE that allows to resume a failed multi-stream backup job from the last checkpoint taken before the failure. Restartable backups are supported for NetWorker 8.1 and later versions and Commvault DMAs. You can enable restartable backups in your DMA.

Note: OneFS NDMP supports backing up file attributes, access control lists, and alternate data streams. 

Run the following command to check the backup type (OP) of the running NDMP session.

# isi ndmp sessions list

For the completed NDMP session, check the backup type (BACKUP_METHOD) through the logs at /ifs/.ifsvar/modules/ndmp/trace.

The following are examples of the NDMP backup type as indicated through the above command or logs.

B(T0): Token based full backup

B(Ti): Token based incremental backup

B(L0): Level based full backup

B(L5): Level 5 incremental backup

B(S0): Snapshot based full backup

B(S3): Snapshot based level 3 backup

B(FT0): Token based full filelist backup

B(FL4): Level 4 incremental filelist backup

B(L0r): Restartable level based full backup

B(S4r): Restartable snapshot-based level 4 incremental backup

B(L7R): Restarted level 7 backup

B(FT1R): Restarted token based incremental filelist backup

B(ML0): Multi-stream full backup